Racemic bupivacaine is an effertive long-acting local anaesthetic, and may be given as an epidural. However, racernic bupivacaine is cardiotoxic, having depresant electrophysiological and mechanical effects on the heart. It should therefore be used with caution in cardiac-compromised patients, and the use of high doses and high concentrations is contraindicated.
In particular, bupivacaine has produced death in a number of patients, including women in childbirth and when used in the Bier's block technique. Although the incidence of death has been relatively small, the concern has been sufficient, to stop the use of 0.75% bupivacaine for obstetrics and the proscribing of bupivacaine for use in Bier's blocks.
In addition, due to its mode of action, directly on the nervous system at higher doses, bupivacaine is known to have undesirable central nervous system (CNS) side-effects which, prima facie, are connected to its anaesthetic activity. Indeed, the occurrence of CNS side-effects is one of the major factors limiting the use of this drug in normal clinical practice employing techniques such as local infiltration, nerve block, field block, epidural and spinal blocks.
It has been suggested that levobupivacaine is less cardiotoxic than dextrobupivacaine and racemic bupivacaine. See, for example, Vanhoutte et al, Br. J. Pharmacol. 103:1275-1281 (1991), and Denson etal, Regional Anaesthesia, 17:311-316 (1992). However, these reports are based on work in vitro, and cannot necessarily be extrapoled to any mammals, and certainly not to humans.
The surprising and effective utility of levobupivacaine in man, in vivo, is evidenced for the firs, time in WO-A-95 10276, WO-A-9510277 and Gristwood et al, Exp. Opin. Invest. Drugs 3(11):1209-12 (1994).
Bupivacaine has been tested, for the treatment of migraine, by infusion of 0.2 mg/kg. Some reliefwas reported. See Pain (1984), Suppl. 2S269. This possibility has not been developed.